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Gender is Hard-wired

Since the 1970’s, the scientific community agreed that gender and sex differences in the brain resulted from “marinating” the embryonic brain in testosterone or estrogen, and those hormones then organized how the brain’s sexual identity would develop. It’s a tidy theory, but one now proven wrong.

He identified 54 genes that determine a brain’s sexual identity before birth, and before hormonal influences upon the fetus. 18 of the genes asserted at higher levels in male brains, and 36 expressed at higher levels in female brains. “We didn’t expect to find genetic differences between the sexes’ brains,” Vilain said. “But we discovered that the male and female brains differed in many measurable ways, including anatomy and function.”

“Our findings may explain why we feel male or female, regardless of our actual anatomy,” Vilain said. “These discoveries lend credence to the idea that being transgender — feeling that one has been born into the body of the wrong sex — is a state of mind.”

1 in 3,000 births are considered “intersex” in that a physician is unable to determine the sex of the newborn. In such cases the doctor and/or the parents arbitrarily “assign” a sex to the infant, and surgery usually constructs genitalia aligned with that assignment. With more information about the genetic markers of sexual identity, families and doctors will be able to make assignments that will later correspond with how the developing person will come to feel about themselves. “If physicians could predict the gender of newborns with ambiguous genitalia at birth, we would make less mistakes in gender assignment,” Vilain said.

Vilain suggests that the research findings may also help to explain the origin of homosexuality. “It’s quite possible that sexual identity and physical attraction is ‘hard-wired’ by the brain,” he said. “If we accept this concept, we must dismiss the myth that homosexuality is a ‘choice’ and examine our civil legal system accordingly.”

The UCLA study received support from the National Institute of Child Health and Human Development, the National Science Foundation and with funding from the UCLA Department of Urology. The report was co-authored by Phoebe Dewing, Steve Horvath and Tao Shi, all of UCLA. To see the original research report, CLICK HERE: